It becomes increasingly important to know the sense of driving during steering by a driver in the performance evaluation or the like of new-model cars and tires. In this case, it is considered to be effective in the performance evaluation or the like to know in detail a force or a moment applied to a steering wheel rim (steering wheel) gripped by a driver during steering.
As a conventionally known detecting apparatus for detecting a force applied to the steering wheel rim (steering wheel) of a vehicle, there are known an apparatus for detecting the position of hands on a steering wheel, which is disclosed in National Publication of International Patent Application No. 2003-535757 (Patent Document 1), a steering wheel with an opto-electronic sensor, which is disclosed in National Publication of International Patent Application No. 2000-500101 (Patent Document 2), and an apparatus for evaluating steering operability by the analysis of a hand force, which is disclosed in Society of Automotive Engineers of Japan, Inc., Preprints of Meeting on Automotive Engineers, No. 55-03, P13-16 (Non-Patent Document 1).
In the apparatus disclosed in the Patent Document 1, sensors are provided in a steering wheel for a vehicle having a steering ring, a hub, and at least one spoke connecting the steering ring and the hub to detect a force applied to a steering wheel rim (steering wheel). The sensors used in the apparatus are divided into plural segments arranged successively in the longitudinal direction of the steering ring. Also, the sensors extend over the entire length of the steering ring and are arranged distributed over the periphery of the steering ring. By arranging the sensors as described above, the position of hands on the steering wheel can be detected by the sensors.
In the apparatus disclosed in the Patent Document 2, an optical sensor including an optical fiber which is wound around a steering wheel for controlling a vehicle is provided. By detecting a change in light signal passing through the optical fiber, the state in which a driver grips the steering wheel is detected.
An apparatus enabling to measure torque during steering by providing a torque sensor in a steering wheel hub is also known.    Patent Document 1: National Publication of International Patent Application No. 2003-535757
Patent Document 2: National Publication of International Patent Application No. 2000-500101